The present invention relates in general to a hard copy printing device suitable for use in conjunction with word processing machines and, more particularly, to an integrated printer and tray paper feeding apparatus which will continuously feed individual sheets of paper and envelopes from an internal supply thereof along a feed path past an integrated printing device to effect printing thereon. The paper is arranged in a stack within a paper tray having means which facilitate the insertion and removal of the paper tray from within the apparatus.
Tremendous advances have been made in the last few years in automating office procedures. Conventional typewriters have grown into mini-computers performing word processing, storage and other functions. The speed at which these machines produce words on paper is increasing at a rapid rate. As added speed and sophistication are developed into such machines, the actual putting of words onto paper becomes auxiliary to the main function of collecting and organizing the information into a format to be printed. In order to have flexibility and speed, many systems have been developed where an operator manipulates words on a cathode ray tube or other word processing equipment until the final copy is in the format desired. With all of these advances, it has developed that today one of the major bottlenecks in terms of time, and therefore usefulness of this equipment, is the rate at which paper can be brought to and moved past a printing head to produce the final hard copy.
Of course, it is possible to use continuous sheets of perforated paper, as is commonly done in computer applications, having sprocket holes along the sides thereof to continuously feed and move the paper through an impact printer. This, however, requires special paper which is not suitable to the many requirements for which normal typewriting is employed.
Many machines exist, both copying machines and printing machines, which automatically feed paper past a printing or reproducing station. These machines are normally run synchronously such that prior to the time that paper is fed, the information to be imparted to the paper is already organized and the paper is moved past the printing head in a continuous fashion. This is not generally suitable for impact printing devices since impact printing is accomplished with the paper stationary rather than moving, and further the adaption of normal typewriting type printing requires the moving of paper not only on an intermittent basis, but also in the forward and reverse direction in accordance with the information to be typed. Still further, with such existing equipment, it is generally not possible to manually feed separate sheets of paper, which may be of a different size or thickness, such as, for example, envelopes, without disconnecting the equipment from the printing apparatus.
In U.S. Pat. No. 4,326,815, which patent is assigned to the same assignee of the present invention, there is disclosed a paper feeding apparatus including a removable paper tray which is capable of being retrofitted with respect to existing printing devices, i.e., distributed as an aftermarket product, as well as being capable of being sold and distributed with the printing device. The retrofit characteristic of this paper feeding apparatus lends itself to conform to the requirements of existing impact printing devices rather than requiring the radical modification thereof so as to conform with the needs of high-speed paper feeding. However, although such paper feeding apparatus has been commercially successful, the retrofit nature of the paper feeding apparatus requires separate installation procedures, separate maintenance to both the paper feeding apparatus and the paper printing device, additional office space to accommodate the retrofitted paper feeding apparatus and, often requires a separate and special sound-proofing enclosure to reduce the noise level resulting from the operation of both the paper feeding and paper printing device. Further, the paper tray of the retrofit apparatus requires the manipulation of a lever before the paper tray can be withdrawn from the apparatus. Unless the lever is manipulated, any attempt to withdraw the paper tray could result in damage to the apparatus. There is therefore a further need for a paper tray which can be inserted and withdrawn from an integrated printer and paper feeding apparatus which will prevent any inadvertent damage thereto.